Tool for capping bottles with screw caps

ABSTRACT

The cap is screwed on by a friction clutch (33) that gives a tightening torque less than the desired ideal torque. The cap (C) gripping head (47) is connected not only to the driven part of the clutch but also, through a composite drive shaft (233, 54), to a freewheel (57) engaging with a mechanism which, after the screwing of the cap by the clutch, is acted on by a wedge (89) of programmable and adjustable interference mounted on a guide connected to a load cell (84). When this mechanism is acted upon by the wedge, it receives from it the small rotation required to complete the screwing of the cap and the reaction of the wedge to the mechanism is detected by the load cell, which emits an electrical signal proportional to the effective tightening torque applied to the cap. In order to protect the mechanical friction clutch (33), the latter is clamped at a constant minimum value which it is possible to adjust via its pressure spring (42), whereas it is clamped to the operating value by a pneumatic servomechanism which is active only during the initial part of the cap screwing cycle.

FIELD OF THE INVENTION

The invention relates to carousel-type machines for closing bottles orthe like with screw caps, and for these machines, which currentlyoperate at sometimes very high speeds, it concerns a highlytechnologically reliable tool that is capable of being programmedthrough the machine control panel to satisfy the leaktight screwingrequirements of the various shapes and/or sizes of bottles and capsacceptable by the carousel, which is able to monitor the screwing torqueapplied to each cap and if necessary also to adjust itself automaticallywith a feedback command, so as to ensure that the screwing torque is andremains at the predetermined level, in order that the caps are closed insuch a way as to ensure the bottles are sealed--a condition which isparticularly necessary for the storage of the packaged product--and atthe same time in order to ensure that the caps can be unscrewedsufficiently easily when the time comes to use the product packaged inthe said bottles.

BACKGROUND OF THE INVENTION

In order to monitor the screwing torque applied to screw caps onbottles, known devices exist with friction clutch means under elasticloading, which act basically as torque limiters. When the tighteningtorque varies the said elastic means must be adjusted. These knowndevices are not capable of producing operating conditions that areconstant over time because of the variable reaction of the frictionclutches in response to temperature, wear and other factors. Other knowndevices use dog clutches instead of friction clutches, loading them bypneumatic pressure which is variable in accordance with tightnessrequirements: when the desired screwing torque is reached one of thetheir components makes an axial movement which is detected by sensors sothat the degree of tightness of the cap can be checked. The operation ofthese devices is however once again unreliable and inconstant over timeas it again depends entirely on a clutch of the friction type.

BRIEF SUMMARY OF THE INVENTION

It is an object of the invention to overcome these and otherdisadvantages of the prior art in the following manner. The cap isscrewed with the aid of friction clutch means that generate a tighteningtorque approximately equal to or slightly less than the desired idealtorque. The shaft which carries the cap gripping head and is connectedto the driven part of the clutch, is connected through a freewheel to amechanism which, after the screwing of the cap by the clutch, is actedon by a wedge of programmable and adjustable interference mounted onmovable means connected to a load cell. When this mechanism is actedupon by the wedge, it receives from it the torque required to completethe screwing action and the reaction of the wedge to the said mechanismis detected by the load cell, which emits an electrical signalproportional to the effective tightening torque applied to the cap. Inorder to protect the mechanical friction clutch the invention alsoprovides for the latter to be loaded at a minimum value by an adjustableelastic means and for the compressive load applied to the clutch to beraised to the required operating value by a piston/cylinder unit that isloaded with a fluid at the predetermined pressure. This conditioncontinues for the period of time required to carry out the first phaseof the cap screwing, after which it is removed so that the clutch isprotected from overheating and wear.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of the invention, and the advantages it offers, willbecome clearer in the following description of a preferred embodimentthereof, illustrated purely by way of non-restrictive example in thefigures of the five attached sheets of drawings, wherein:

FIG. 1 is a longitudinal section through one of the tools for screwingon a screw cap, seen in the active working phase;

FIG. 2 is an enlarged view of the lower end of the tool seen in FIG. 1,with the cap gripping head and the mechanically and pneumatically loadedclutch that brings about the first stage of rotation of the grippinghead;

FIGS. 3 and 4 show details of keying with the possibility of axialmovement for parts of the tool of FIG. 1, in section on planes III--IIIand IV--IV, respectively;

FIG. 5 shows the upper section of the capping carousel carrying thetools in question, and seen in section on a vertical plane containingthe axis of rotation of the said carousel;

FIG. 6 is a top-down view of the top of the capping carousel seen inFIG. 5; and

FIG. 7 is a schematic block diagram of the principal parts of theelectrical and pneumatic circuit controlling the capping carousel withits tools according to the invention.

FIGS. 8a and 8b show in longitudinal section respectively the upperportion and the lower portion of a modified embodiment of one of thetools for screwing on a screw cap.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, A is a general reference for one of the vertical tools forclosing bottles B or the like (only partly visible) with a screw cap C.The tool A is mounted with other identical tools, in the correct numberand with equal angular spacing, around the periphery of a carousel thatturns on a vertical axis. The details of the carousel are not shown asthey are known in the sector of the technology to which the inventionrelates. The bottle B is fed in by suitable means underneath eachcapping tool A, aligned axially with the tool and held steady bysuitable supporting means (not shown) and by a gripping head (notshown), the supporting means and gripping head being connected to thecarousel, with which they rotate. When there is a change to the shapeand/or size of the bottles to be capped, known means are provided forraising or lowering the entire upper section of the carousel with itscapping tools relative to the said bottle supporting and steadyingmeans, which remain at a fixed height.

In FIG. 1 the reference 1 indicates the upper plate of the carousel thatrotates about a vertical axis and supports rotatably in bearings 2 theupper end of a vertical tube 3 which extends downwards. The plate 1 ismade hollow and contains a gear 4 keyed by the key 5 to the said tube 3and meshing with epicyclic gears of which a final component is marked 6and which provides, for example, a fixed or contrarotating part in axialalignment with the carousel (not shown), such that as the plate 1rotates about the vertical axis of the carousel, the gear 4 derives fromthe said epicyclic gears, and transmits to the tube 3, the rotationrequired to screw the cap (see below).

A tube 7 fits telescopically around the section of the tube 3 below theplate 1 and passes through guide bushes 8, 108 mounted in correspondingvertical seats in an intermediate horizontal plate 9 and in a lowerhorizontal plate 109 of the carousel, these plates being fixed to eachother and to the plate 1 by means of annular jackets 101 and 201coaxially positioned in the carousel and with suitable openings for thepassage of various components. The top end of the tube 7 passes, withlateral leaktightness provided by the seals 10, through a cylinder 11inside which there operates a laterally sealed piston 18 fixed axiallyto the said tube. The body of the said cylinder 11 extends towards theaxis of the carousel and is fixed to a vertical plug 12 that leads downuntil its lower end passes through a vertical seat 13 formed in the saidlower plate 109 of the carousel, in such a way that the said cylinder 11is unable to rotate and can only make axial movements. Fixed to the sideof the cylinder 11 nearest the axis of the carousel, in a radialarrangement relative to the carousel, is the horizontal spindle of aroller 14 engaged in the double-acting profile 15 of a known annular cam16: the latter, which is situated coaxially with the carousel andmounted on the carousel's fixed part 17, is designed to control theapproach to the bottle B of the movable lower part of the tool of theinvention, carrying the cap C to be screwed into place (see below).

Inside the cylinder 11 there are two pressure chambers 19 and 20. Theseare defined by the opposite faces of the piston 18 and are connected tolines delivering a fluid at different pressure values. Specifically,pressure is created inside the lower chamber 19 to push the piston 18upwards with sufficient force to compensate for and substantially cancelout the weight of the movable lower part of the tool which carries thecap and which is intended to press on the bottle. A constant pressure isset up inside the upper chamber 20 to oppose screwing, in such a waythat, if during the phase of approach and screwing the cap jams on thethreaded mouth of the bottle and refuses to screw down, the cylinder 11can continue to move down while the tube 7 maintains a stationaryheight, thereby avoiding damage to the cap and bottle and the associatedconsequences. If this happens, the chamber 20 reduces in volume and itspressure would tend to rise if calibrated means (not shown) were notprovided, such as a pressure relief valve, to switch and maintain thepressure in the said chamber at a constant and predetermined value. Inaddition to these means there may also be transducers indicatedschematically at 120, e.g. a pressure switch, to detect the interventionof the said calibrated means or some equivalent function and signal tothe processor controlling the machine (see below) that a particular toolA has malfunctioned.

Mounted on the said fixed part 17 of the carousel that supports the cam16 is the fixed part 21 of a rotary distributor, to which are connectedthe compressed air delivery lines and with which there engages, by meansof the bearings 22 and seals 23, the rotating part 24 of the distributorwhich is fixed to the plate 1 and from which the lines shownschematically as a whole at 25 branch off in order to supply thecompressed air to the said chambers 19 and 20 and to other pressurechambers within the tool (see below).

The tube 7 is prevented from rotating by a projection 26 on its side: bymeans of a bush 27 at its extremity, this projection moves in a guidedway up and down the plug 12. The lower end of the tube 3 engages bymeans of keys 28, held in place by transverse pins 29 (see detail FIG.3), with the longitudinally grooved upper end of a pipe 30. This pipe 30is mounted in bearings 31, 32 to enable it to rotate inside the tube 7,and ends in a bell 130 that forms the driving part of a multiple-discfriction clutch 33. The lower driven part 133 of this clutch 33 ismushroom-shaped, is mounted rotatably by means of bearings 34 inside abush 35 housed in the lower end of the tube 7, which extends beyond thebell 130 of the clutch, without interfering with the latter, and whichis held axially in position by a nut 37 screwed into the correspondingtapped end of the tube 7. The bush 35 carries on its lower end a collar38 fastened by screws 39, for the purpose of securing the said bush tothe nut 37 and making it integral therewith. By slackening the screws 39the collar 38 can be turned with an appropriate tool and, with it, thebush 35, so that the tapped part of its upper end screws an externallythreaded retainer 40 up or down. The retainer 40 is prevented fromrotating by a pin 41 held by an inward projection of the tube 7, whichmeans that the said retainer can only move axially. The retainer 40 actson the end of a cylindrical helical spring 42 whose other end presses ona retainer 43: this is keyed by a key 44 to the bush 35 and supports thelower bearing 32 of the pipe 30. By adjusting the load of the pressurespring 42, the pressure between the driving parts and the driven partsof the clutch 33 is modified, and this defines the limit value of thetorque within which the said parts remain rotationally coupled to eachother.

The driven parts of the clutch 33 also include a shaft 233 that passesaxially and accurately through the hollow leg of the saidmushroom-shaped driven part 133, which is coupled to it by the key 45and which, by means of the keys 46, is integral with the driven discs ofthe said clutch. The lower end of the shaft 233 and of the leg of thedriven part 133 of the clutch are provided with a quick-action couplingof known type for the keyed attachment of the known, usuallypneumatically operated gripping head 47, which holds the cap as itscrews it onto the bottle.

The lower part of the pipe 30 is inside a tubular rod 48 towards the topof which is a piston 49 with seals 50: this piston slides inside apressure chamber 51 formed inside the tube 7. A line 52 leads into thischamber and is connected to means for the supply of a fluid, for exampleair, at the correct pressure. The value of the engagement torque of theclutch 33 is determined partly by the load of the spring 42 and partlyby the pneumatic pressure transmitted by the piston 49. According to theinvention the load exerted by the pressure spring 42 is a minimum valuethat is the same for all the tools A of the carousel, produced bytightening the aforesaid bushes 35 with a torque wrench. According tothe invention, moreover, this value may remain constant even when thereare changes to the shape and/or size of the bottles and of their capswhich the present carousel is capable of screwing onto them--at leastwithin a certain range of shapes and/or sizes. The value of theengagement torque of the clutch 33 is adjusted on each occasion to thespecific requirements of the bottles and caps being processed, byadjusting the pneumatic pressure acting on the piston 49 via the machinecontrol panel, using appropriate means indicated below. To protect theclutch, moreover, this pneumatic pressure is supplied for only a part ofthe cap screwing phase, as stated below.

The shaft 233 that supports the cap C gripping head 47 engages a sectionof the pipe 30 with a radial play such that it can fit, with the seal 53for lateral leaktightness, in the tubular end 154 of a composite shaft54. This shaft 54 is mounted rotatably in the tube 3 on bearings 55 andis provided at the lower end of its core within the said tubular part154, with a diametrical incision 56 containing a flattened part 333 ofthe said shaft 233 which is thereby keyed to the upper shaft 54 but withthe ability to move axially relative to the latter (see also detail FIG.4). The shaft 54 projects above the top of the plate 1 sufficiently totake a freewheeling gear 57, of which more later, and the very top ofthe same shaft 54 is fitted with a rotary coupling 58 connected to acompressed air delivery line for closing the gripping head 47 which isnormally held open by spring means. The compressed air reaches theinternal piston/cylinder unit controlling the gripping head 47 afterpassing through holes indicated generally by the reference 59, which runaxially through the composite shaft 54, the subsequent shaft 333, 233and the coupling part of the said gripping head.

The air lines, whose pressure must be adjustable to enable the frictionof the clutch 33 to be set at the use level and the gripping head 47 tobe closed, come from respective valves bearing the general reference 60.The valves 60 are mounted on a bell-shaped support 61 fixed coaxially tothe plate 109 and also partly mounted directly on this plate. They areacted upon by cams 62 keyed 63 to the fixed body 64 of a rotatingdistributor connected to fixed air supply lines (not shown). Therotating part 65 of the distributor, which acts in combination with thesaid fixed part 64, is fixed to the frame 61 and is the starting pointfor the various lines indicated by the general reference 66 whichconnect to the various aforesaid valves 60. The outlets of the valves 60are connected to the rotary coupling 58 and to the pressure chamber 51of the various tools A.

As can be seen in FIGS. 1, 5 and 6, the freewheeling gear 57 is in meshwith a gear 67 mounted so as to rotate via its vertical shaft 167 on theplate 1 and carrying an eccentric roller 68 with a vertical axis toengage with the annular grooved profile 169 of a flat cam 69 that isfixed via a collar 70 to a horizontal plate 71 integral with a fixedaxial part 171 of the carousel. The profile 169 of the cam ischaracterized by a long section of circular form concentric with theaxis of the carousel and by a short section in which the same profilemaintains the circularity of the outer flank, while the inner flankbecomes a straight chord, as indicated at 169' in FIG. 6, so that inthis section the said grooved profile is broadened out to an appropriateextent towards the carousel axis. In the vicinity of this broadenedsection of the cam profile the body of the same cam has a side 172 of awindow 72 of e.g. square shape, which exposes the greater part of theunderlying plate 71. At right angles to the said side 172 of the window72 are two horizontal guide rods 73 attached by their ends to the collar70. A slider 74 runs on these rods and is hinged on the underside to theend of a slotted link 75 keyed to the end of a vertical tube 76. Thistube rotates in the said fixed part 171 of the carousel and is connectedat its lower end to precision means for modifying and stabilizing itsangular position, which may be a servomechanism with encoder shownschematically at 77, designed for remote control via the machine controlpanel (see below). Mounted on the slider 74 are two guides 78 parallelto the rods 73 mentioned earlier: able to slide inside them are rods 79whose ends are fixed to crossmembers 80, 180, of which crossmember 180is connected to the rods of two piston/cylinder units 81, 181 that lieparallel with the rods 79 and whose bodies are fixed to the said slider74. These cylinders are normally in the position of maximum extension oftheir rods, that is to say such as to hold crossmember 80 against theguides 78 and the cylinders are connected to a pneumatic logic circuit82 mounted on the top face of the cam 69 and having the functions statedbelow. Fixed at 83 to one end of crossmember 80 is the end of anelectrical load cell 84 parallel to the said crossmember and with itsother end connected, via a joint 85, to a slider formed by twohorizontal and mutually parallel rods 86. These lie at right angles tothe said crossmember 80, slide in corresponding guide seats 87 withinthe body of the cam 69 and project into the initial section of thebroadened section of the cam profile, where the said cam comprises aslot 88 which is parallel to the said seats 87 and in which a slidingwedge 89 is guided with its side at an angle to enable it to enter thecam 69 profile 169 from the outside and interfere by a predeterminedamount, controllable remotely by means of the servomechanism 77, withthe roller 68 of each gear 67 of each tool A of the capping carousel. InFIG. 6 the wedge 89 is illustrated in the position of maximuminterference with the cam 69 profile.

The electrical lead 184 connected to the load cell 84 runs down theaxial cavity of the tube 76 (FIG. 7) and connects to the machine controlpanel (see below).

The pneumatic logic circuit 82 is connected to one of the outlet lines25 of the upper rotary distributor of the carousel and contains, forexample, components comparable with the triggers and flip-flops ofelectronics, such that the cylinder 81 is normally kept extended with apressure that tends to protect the load cell, that is to say by ensuringthat the load cell is never stressed beyond a maximum predeterminedvalue. The cylinder 181 on the other hand is normally not supplied withfluid. The circuit supplying cylinder 81 may contain, for example, atrigger that is thrown when a critical pressure is exceeded due to ananomalous stress on the load cell, and, after an interval of time suchas to ensure that the roller 68 of the detected unit A has released thewedge 89, delay means cause a change of state in a flip-flop componentwhich then supplies air to the cylinder 181 at a pressure that willensure the rapid extension of the rod of this cylinder and the rapidreturn to rest of the entire movable system connected to this cylinder,after which the air supply is stopped and the tool returns to thestart-of-cycle condition.

The operation of the tool will now be described beginning with the phasein which a cap C is screwed onto a bottle B, which is partly visible inFIG. 1. The carousel turns clockwise from the point of view of a personviewing FIG. 6 and the rollers 68 of the gears 67 of the variouscarousel tools A travel along the circular section of the cam 69 profile169. The cap C held by the closed gripping head 47 (FIG. 1) comestowards and contacts the mouth of the bottle by the action of the cam 16and rotates in the screwing direction by the engagement of the gear 4with the epicyclic gears indicated partly at 6. The cap screws onto thebottle with a corresponding lowering of the tube 7 and a correspondinglowering of the piston 18, in opposition to the pneumatic pressure thatis balancing the weight of the tool. If, during the lowering of the toolby the cam 16, the cap becomes stuck on the neck of the bottle andrefuses to screw down, the tube 7 remains at a stationary height whilethe cylinder 11 continues to be lowered, thus reducing the volume of thechamber 20 as stated earlier.

While the cap is being screwed on, compressed air is being sent into thepressure chamber 51 to load the clutch 33 with the necessary force toreach the desired screwing torque at the cap--which is a value slightlyless than the ideal predetermined maximum value. During the screwing ofthe cap the driven part 133 of the clutch rotates and with it the shafts233 and 54, while the freewheel 57 remains stationary and thecorresponding gear 67 also remains stationary, together with the roller68 which travels in the circular section of the cam 69 profile 169. Whenthe cap has been screwed to the tightening torque determined by thefriction clutch 33, the compressed air supply to the chamber 51 is cutoff at the appropriate moment so that the said clutch continues throughthe remaining part of the operating cycle with only the elastic loadproduced by the action of the pressure spring 42, the purpose here beingto limit the friction, overheating and thereby protect the life andreliability of the clutch. The gripping head 47 stops and, with it, thedriven parts of the clutch and the shafts 233, 54 cease to rotate. Inthe next step the rollers 68 on the gears 67 of the various tools A ofthe carousel (see FIG. 6) arrive at the broadened section of the cam 69profile 169 and engage with the wedge 89 which, because of the degree ofinterference on the orbit of rotation of the rollers, causes ananticlockwise rotation of the gears 67 of a predetermined angularamplitude and this rotation is passed on through the freewheel 67 to theshaft assembly 54, 233, to the leg 133, to the gripping head 47 and soto the cap C, which is screwed with the predetermined tightening torque.It will be obvious that in this phase the gear pair 57, 67 and theentire assembly connected to the gripping head 47 starts from asituation of rest and that it is therefore free of inertia that couldproduce an error in the value of the transmitted twisting moment,thereby guaranteeing the operating precision of the entire tool. Duringthis stage the interference of the roller 68 with the inclined surface89 generates a force on the load cell 84, which produces a proportionalsignal by which it is possible to measure the tightening torque appliedto the caps and it is consequently possible to certify the degree ofclosure of all the bottles treated by the capping carousel. If a cap orthe neck of a bottle have defects, so that the load cell 84 detects atorque less than or greater than predetermined values, the correspondingbottle or bottles will be prepared for removal at the exit of thecapping carousel by means of known type that will be notified of thesuccessive linear and angular position of the bottles by encodersmounted on the central shaft of the capping carousel and on thesubsequent means of conveyance of the bottles.

When the characteristics of the bottles and of their closing caps arevaried it will be possible to adapt the capping carousel to thedifferent screwing requirements of the caps by varying the pneumaticpressure in the chamber 51 and/or varying the degree of interference ofthe wedge 89 with the profile 169 of the cam 69 in accordance with aknown program.

When the rollers 68 of the gears 67 leave the wedge 89, the same rollersengage with the rectilinear chord section 169' of the inner side of thecam 69 profile and are returned by the latter to the original angularposition, serving for their reinsertion into the circular part of thecam profile.

Referring to FIG. 7 it will be seen that by means of the processor 90which controls the operation of the capping machine, it will be possiblefor example to control, by means of a suitable interface 91, a firstpneumatic unit 92 which, by means of the upper rotary manifold 21, 24,supplies the chambers 19 and 20 of the various tools A at the pressurevalues required on each occasion for the weight of the gripping heads 47and for the characteristics of the caps and of the bottles to be closed,and which supplies the pneumatic logic circuit 82 with the pressure(s)necessary for supplying at different times the cylinders 81, 181 whichrespectively damp out any anomalous stresses to which the load cell 84may be subjected and return the latter to the rest position.

Using the processor 90 it will also be possible to control a secondpneumatic unit 93 designed to provide pressure at values that may beselected according to the characteristics of the bottles and of theirclosure caps: the pressure is supplied via the lower rotary distributor64, 65 and through the valves 60 to the rotary couplings 58 for thecommand to close the gripping heads 47 with a predetermined pressure andis sent to the lines 52 leading into the pressure chambers 51 of thepiston/cylinder unit by which the clutch 33 is loaded to the maximumworking pressure.

The servomechanism 77 that modifies the degree of interference of thewedge 89 with the orbit of rotation of the eccentric rollers 68 on thegears 67 of each tool, and that helps to modify the tightening torqueapplied to the screw caps, may be controlled by the processor 90 throughanother interface 94. The electrical lead 184 carrying the signalproduced by the load cell 84 is connected to the interface 94 which canbe prepared to use this signal as a feedback signal in orderautomatically to instruct the servomechanism 77 to modify theinterference of the said wedge 89 to the value set by the workingprogram of the processor. 95 denotes the phase signal input from thecapping machine. If the processor 90 receives from the load cellincorrect values for the tightening torque of a cap and detects, via theoptional sensor 120, defects in the first stage of the screwing of acap, it will send a command through its output 96 for the removal fromthe processing line of the corresponding incorrectly closed bottle.

To the tool A for screwing on the cap C there can be made the followingconstructive modifications, which will be now described with particularreference to FIGS. 8a and 8b. It is to be noted that in accordance withthe embodiment of FIG. 1, the driven portions of the clutch 33 arepermanently connected with the shaft 233, also when the tool A performsthe final screwing of the cap by means of the freewheel 57 and the wedge89 as above mentioned. The frictions originated by the said driven partsof the clutch sum up with the resistance created by the cap during itsscrewing and can cause a distortion of response in the whole system. Inorder to eliminate this drawback, as shown in FIG. 8b, the shaft 233 isconnected to the driven portion 133' of the clutch 33, with theinterposition of a unidirectional coupling mechanism 97 of the typeemployed in the freewheel mechanisms, which is active whenever themotion must be transmitted from the driven portion 133' to the shaft 33but which is inactive on the contrary case, so that when the shaft 233is actuated for the final screwing of the cap, the whole driven assemblyof the clutch is isolated.

The embodiment illustrated with reference to FIG. 1, which contemplatesthe use of the cylinder 11 with the lower pressure chamber 19 for thecompensation of the weight of the assembly which carries the grippinghead 47 and the upper pressure chamber 20, creates an elastic systemwhich can give a relatively slow and not so accurate response. To thesaid inconvenience there can be obviated by eliminating the abovementioned pneumatic system, as shown in FIG. 8a and, as shown in FIG.8b, the gripping head 47 is provided with a tang 147 telescopicallymounted in the terminal portion of the shaft 233, rotatably coupled withthis latter by means of the key 98 and prearranged in such a manner asto perform a limited axial movement against the action of a spring 99.Any resistance to the screwing of a cap originates a relative axialmovement between the parts 147 and 233 with compression of the spring99.

A further modification made to the solution according to FIG. 1 consistsin the use of a small tube tightly connected to the upper end of theaxially hollow tang 147 of the gripping head 47, said tube axiallytraversing the unit of the shafts 233 and 54 and projecting from the topend of this latter for its connection to the coupling 58 for thecompressed air required for the operation of the gripping head 47. Thissolution simplifies the construction of the tool since it avoids theprovision of air tight connections between said hollow shafts 233 and54.

We claim:
 1. A tool for capping containers with screw caps which saidtool is mounted around a periphery of a rotating carousel with otheridentical said tools in a capping machine, said tool comprising:agripping head with which the cap is gripped and screwed onto thecontainer; a friction clutch having a driving part and a driven partconnected to said gripping head; a first torquing device which screwsthe cap on the container at a lower screwing torque which is lower thana predetermined maximum screwing torque for the cap, said first torquingdevice includinga) a rotation means for providing axial rotation fromrotary movement of the carousel to said driving part of said frictionclutch, and b) a calibration mechanism by which the axial rotation ofsaid rotation means provided to said driving means is calibrated toprovide the lower screwing torque to said driven part and hence to saidgripping head which lower screwing torque is lower than thepredetermined maximum screwing torque for the cap; and a second torquingdevice which further screws the cap on the container to achieve acomplete screwing of the cap on the container to the predeterminedmaximum screwing torque, said second torquing device includinga) afreewheel in axial alignment with said friction clutch and connected tosaid driven part, b) a non-rotating mechanism which is connected to saidfreewheel to impart to said freewheel a rotation and hence to rotatesaid driven part after the lower screwing torque is applied to the cap,and c) a static opposing means which is engaged by said non-rotatingmechanism upon rotation of said freewheel on the carousel so that saidfreewheel which is initially at a rest position without any inertia andhence said gripping head are then rotated, by engagement of saidnon-rotating mechanism with said static opposing means, through anadjustable and predetermined angle to achieve a complete screwing of thecap on the container to the predetermined maximum tightening force.
 2. Atool for capping containers with screw caps as claimed in claim 1,further comprising:a transducer means for detecting a stress to whichsaid static opposing means is subjected by engagement with saidnon-rotating mechanism and for generating an electrical signalproportional to the maximum screwing torque; and a processing means forprocessing the electrical signal produced by said transducer means, forcomparing the processed electrical signal with predetermined values, andfor actuating a removal device for removal of a container from thecarousel when the compared signals are indicative of a defectivelyscrewed cap.
 3. A tool for capping containers with screw caps as claimedin claim 2, wherein said friction clutch includes:a pressure springwhich clamps said driving part and said driven part together with aminimum load; and a pneumatic means for pneumatically clamping saiddriving part and said driven part together at a variable load in excessof the minimum load provided by said pressure spring only when saidgripping head is screwing the cap to the container such that when saidgripping head is not screwing the cap to the container only the minimumload of said pressure spring is clamping said driving part and saiddriven part together.
 4. A tool for capping containers with screw capsas claimed in claim 3:wherein said carousel of the capping machineincludesa) a fixed part on which said static opposing means are mounted,b) an upper horizontal plate which rotates, which has bearings therein,and on which said non-rotating mechanism is mounted, c) an epicyclicgear which rotates as the upper plate rotates and which engages saidfixed part, d) an intermediate horizontal plate fixed to said upperplate, e) a lower horizontal plate fixed to said intermediate plate, f)a roller, and g) an annular cam fixed coaxially to said fixed part andhaving a grooved lateral profile which said roller follows to move thecontainer up to said gripping part; wherein said rotation meansincludesa) a first vertical tube supported rotatably by the bearings ofsaid upper plate, b) a gear keyed to said first tube which meshes withsaid epicyclic gear, c) a second vertical tube which is mountedtelescopically and axially movable around an outside of a lower end ofsaid first vertical tube, which is supported by said intermediate plateand said lower plate, and which is integral with said roller, d) ananti-rotation means for preventing said second tube from rotatingrelative to said intermediate plate, e) a weight compensating means forcompensating for the weight of said second tube, said friction clutchand said gripping head relative to said intermediate plate, and f) apipe which is mounted for rotation in said second tube, which is keyedto the lower end of said first tube for axial movement relative thereto,and which has a lower end connected to said driving part of saidfriction clutch; wherein said friction clutch is mounted axially insideof said lower end of said pipe and includesa) a connection between saidlower end of said pipe and said driving part, b) a quick action couplingbetween said driven part and said gripping head, and c) an adjustingmeans for adjusting the minimum load of said pressure spring; whereinsaid gripping head includes a pneumatic holder for the cap; and whereinsaid second torquing device includesa) a composite drive shaft which hasa modifiable length, which is rotatably mounted in said first tube,which extends into said second tube, which has a bottom end connected tosaid driven part, which is axially hollow, and which has a projectionprojecting from a top end of said first tube and keyed to saidfreewheel, and b) a rotary coupling connected to the projection of saidcomposite drive shaft which supplies pressurized fluid through saidcomposite drive shaft to said pneumatic holder of said gripping head. 5.A tool for capping containers with screw caps as claimed in claim4:wherein said weight compensating means includesa) a piston which isintegral with the upper end of said second tube, b) a cylinder in whichsaid piston slides and through which said second tube passes, saidcylinder extending in a direction of an axis of rotation of saidcarousel, supporting said roller which is mounted on a horizontal axis,and having an upper chamber and a lower chamber formed on opposite sidesof said piston, and c) an injection means for injecting into andmaintaining a fluid at varying pressures in said chambers such that (i)a pressure in said lower chamber compensates for the weight of saidsecond tube, said friction clutch and said gripping head relative tosaid intermediate plate, and (ii) a pressure in said upper chamber actsas a damper to provide a predetermined axial force of the cap on thecontainer and so that if the cap becomes stuck and does not screw downsaid second tube does not move down as said roller moves in said annularcam; and wherein said anti-rotation means includesa) a vertical,downward-oriented plug which is fixed to said cylinder, b) a verticalseat which is fixed to said lower plate and in which said plug slides ina guided manner, and c) a bush which is integral with a projection on aside of said second tube and in which said plug is engaged.
 6. A toolfor capping containers with screw caps as claimed in claim 5, whereinsaid injection means of said weight compensating means includes amaintaining means for maintaining at preset and constant values thepressures injected in said upper and lower chambers even when a volumeof said upper and lower chambers vary as said roller follows saidannular cam.
 7. A tool for capping containers with screw caps as claimedin claim 5, wherein said weight compensating means further includes adetecting means for detecting a reduction in volume of said upperchamber as said roller follows said annular cam during a downwardcapping action, said detecting means being connected to said processingmeans so that detection of a reduction in volume is sensed by saidprocessing means as an anomaly of the screwing on of the cap.
 8. A toolfor capping containers with screw caps as claimed in claim 4:whereinsaid friction clutch further includesa) a bell which is integral withthe lower end of said pipe and which internally includes integral firstdiscs spaced from one another, b) second discs spaced from one anotherand interleaved with said first discs, said second discs being fixed bykeys to the bottom end of said drive shaft, c) a mushroom-shaped portionof said driven part which is axially hollow and which is keyed to thebottom end of said drive shaft, d) a bush which is housed in the lowerend of said second tube, which includes bearings which mount saidmushroom-shaped portion for rotation therein, and which extendsvertically above said discs, e) a nut which is threadably received inthe lower end of said second tube and which axially retains said bush inthe lower end of said second tube, f) a ring which is threaded onto atop of said bush and which is engaged on a lower side thereof by saidpressure spring, g) a pin which is integral with said second tube andwhich engages said ring to prevent said ring from rotating about saidsecond tube, h) a retainer which bears against an upper part of saidbell and which is engaged on an upper side thereof by said pressurespring such that by rotary movement of said bush said ring is threadablymoved up and down relative to said bush to vary the clamping loadexerted by said pressure spring on said discs, and i) a bearing whichbears against said bell and which rotatably mounts said retainer aboutsaid pipe.
 9. A tool for capping containers with screw caps as claimedin claim 8:wherein said friction clutch further includesa) a collarwhich axially engages said nut, and b) screws which fix said collar to abottom end of said bush such that rotation of said collar rotates saidbush when said screws are loose but such that no rotation of said collarand said bush is possible when the screws are tightened which causessaid collar to frictionally engaged said nut; and wherein said bush andsaid nut are removable from said second tube together with said discs,said bell, said mushroom-shaped portion and said pipe.
 10. A tool forcapping containers with screw caps as claimed in claim 8:wherein saidpneumatic means includesa) a hollow rod which is located axially insideof said ring, which is axially movable about said pipe, and which restsat a lower end thereof on said retainer, b) a piston which is integralwith said hollow rod, c) a cylindrical chamber formed by a portion ofsaid second tube and a top of said piston, and in which said pistonaxially moves along said second tube, and d) a fluid pressure means forsupplying fluid pressure to said cylindrical chamber in order toincrease the load on said discs.
 11. A tool for capping containers withscrew caps as claimed in claim 4:wherein said carousel of the cappingmachine includesa) a secondary upper plate fixed to said upper plate, b)a second cam having a closed groove profile and fixed coaxial to saidsecondary upper plate, said profile having(i) a primary profile portionwhich is circular and concentric with an axis of rotation of saidcarousel for about 75% of a revolution, and (ii) a secondary profile fora remaining 25% of the revolution, said secondary profile having anouter flank which maintains a circularity of said primary profileportion and an inner flank which is straight and traces a chord, and c)a radial slot at a beginning of said secondary profile in the outerflank thereof; wherein said freewheel of said second torquing devicefurther includes a freewheeling gear mounted to the top end of saiddrive shaft; wherein said non-rotating mechanism of said second torquingdevice further includesa) a corresponding gear which meshes with saidfreewheeling gear, which has a greater diameter than that of saidfreewheeling gear, and which is rotatably mounted about a vertical axisto said upper plate, and b) a roller which is mounted on a vertical axisto a face of said corresponding gear at an eccentric position to thevertical axis of said corresponding gear and which engages said secondcam; and wherein said opposing means includesa) a wedge in said slothaving a slopping face sloping towards the inner flank of said secondaryprofile, and b) a guide means for mounting said wedge in said slot suchthat said slopping face of said wedge is engaged by said roller as saidroller moves along the outer flank of said secondary profile of saidsecond cam, such that as said wedge is engaged by said roller an angularrotation of defined amplitude is imparted to said roller which is inturn imparted through said freewheeling gear to said gripping head andhence to the cap, and such that after passing said wedge said rollerreturns to an original angular position by engagement with the straightinner flank of said secondary profile.
 12. A tool for capping containerswith screw caps as claimed in claim 11:wherein said carousel of thecapping machine includesa) an intermediate collar which is supported bysaid secondary upper plate and which in turn supports said second cam,and b) a window in a center of said second cam; wherein said opposingmeans includesa) a pair of horizontal guide rods which have endssupported by said intermediate collar and which are oriented parallel toa longitudinal axis of said radial slot, b) a horizontal slider which ismounted to said pair of guide rods and which moves thereby in saidwindow, c) a slotted link connected to an underside of said horizontalslider, d) a vertical tube positioned axially and having an upper end towhich said slotted link is connected, e) a servomechanism connected to alower end of said vertical tube by which a position of said slider ismodified, f) a plurality of guides mounted to said slider parallel tosaid guide rods, g) a corresponding plurality of respective rods whichrun in a respective said guide, h) proximal and distal cross memberswhich are parallel and which connect together proximal and distal endsof said rods running in said plurality of guides, said proximal crossmember being adjacent said wedge, i) a load cell having a first endfixed to said proximal cross member and a second end, j) a joint towhich the second end of said load cell is connected, k) a pair ofhorizontal rods which are attached at one end to said joint, which areparallel to said plurality of guides, and which carry at the other endsaid wedge, l) guide seats formed in said second cam in which said pairof horizontal rods slide, m) at least one piston/cylinder unit which isattached to said slider, and which loads said load cell mounted to saidproximal cross member towards an end-of-travel position at saidplurality of guides, n) an air pressure supply which feeds air to saidpiston/cylinder unit such that said piston/cylinder unit reactselastically and protects said load cell if said load cell is subjectedto excessive force during an interference of said wedge and said roller,and o) a means for detecting a load exerted on said load cell and forindicating a value for an effective screwing torque exerted on the capscrewed onto the container, said means for detecting including anelectrical lead running from said load cell and through an axial cavityin said vertical tube.
 13. A tool for capping containers with screw capsas claimed in claim 12:wherein said opposing means further includesa) asecond piston/cylinder unit which is parallel to said first-mentionedpiston/cylinder unit, and b) a controlling logic device which connectssaid first-mentioned piston/cylinder unit to said air pressure supplyand which also connects said air pressure supply to said secondpiston/cylinder unit upon activation of said first-mentionedpiston/cylinder unit to rapidly return to a rest position said load cellafter a delay which allows said roller to disengage from said wedge. 14.A tool for capping containers with screw caps as claimed in claim12:wherein said carousel of the capping machine further includesa) aprocessor which controls an automatic operation of the capping machine,b) an interface connected to said processor, c) a first pneumatic unitwhich is connected to said interface and which supplies a constantpressure compressed air, d) a first rotary distributor which isconnected to said first pneumatic unit, which is arranged coaxially inan upper part of said carousel, and which distributes the compressed airto (i) said upper chamber and said lower chamber of said cylinder and(ii) said controlling logic device, e) a second pneumatic unit whichsupplies a variable pressure compressed air and which is connected tosaid interface, f) a second rotary distributor which is connected tosaid second pneumatic unit, and which is arranged coaxially in a lowerpart of said carousel, g) a first cam actuated valve which is mounted ona rotary part of said carousel, and which has an outlet connected to arotary coupling which supplies air pressure to said gripping head, h) asecond cam actuated valve which is mounted on the rotary part of saidcarousel, and which has an outlet connected to a rotary coupling whichsupplies air pressure to a pressure chamber which loads said frictionclutch with an axial load, and i) a monitoring logic unit which isconnected to said processor, which receives an electrical signal fromsaid load cell, which receives a phase signal from the capping machine,and which compares the electrical signal from said load cell and thephase signal from said capping machine with predetermined values suchthat if the predetermined value is exceeded said processor commands adefectively screwed cap and an associated container to be removed fromthe capping machine, said monitoring logic unit also being connected tosaid servomechanism such that a feedback signal of the electrical signalis used to modify the position of said slider.
 15. A tool for cappingcontainers with screw caps as claimed in claim 4, wherein said secondtorquing device further includes a freewheel mechanism which connectssaid driven part with said composite shaft and which is active only fortransmitting motion from said friction clutch to said composite driveshaft when said freewheel is driven.
 16. A tool for capping containerswith screw caps as claimed in claim 12:wherein the upper end of saidsecond tube is integral with said roller; wherein said friction clutchfurther includesa) a tang which is fitted into and keyed for axialmovement to the lower end of said composite shaft and which is attachedto said gripping head for rotating said gripping head, and b) a springwhich is compressed by an axial movement of said tang when said grippinghead meets resistance to the screwing of the cap onto the container. 17.A tool for capping containers with screw caps as claimed in claim16:wherein said tang is axially hollow; wherein said friction clutchfurther includes a small tube which axially traverses said compositeshaft, which is connected at a lower end to said tang, which projectsupwardly from said composite shaft and connects to said rotary coupling.